Arrhythmia Research Keeps Hearts Beating Steadily

Contact: Toni Searle, [email protected]

CLEVELAND -- "Music has charms to soothe a savage breast," said William Congreve, the English dramatist. Yoram Rudy relies more on science and technology to tame erratic heart rhythms.

Rudy, professor of biomedical engineering at Case Western Reserve University, has spent the last two decades exploring the electrical activity of the heart to learn more about abnormal heart rhythms called arrhythmias.

More than 400,000 Americans die each year from these rhythm disorders, notes Rudy, who is founding director of CWRU's Cardiac Bioelectricity Research and Training Center. He believes that understanding the mechanisms for these abnormal rhythms could save lives through better diagnosis and treatment of cardiac arrhythmias.

The National Institutes of Health's National Heart, Lung, and Blood Institute has renewed support amounting to $2.6 million over the next five years for two of his critical research projects.

The NIH also recently selected Rudy for its MERIT (Method to Extend Research in Time) Award, which could extend his research support for an additional 10 years. The MERIT Award provides long-term, stable support to investigators whose research competence and productivity are distinctly superior, and who are likely to continue to perform in an outstanding manner.

Rudy and his collaborators use theoretical techniques such as mathematical modeling and computer simulations combined with experimental and clinical data to find out why these rhythm disorders occur, where they originate from, and what might be done to prevent or treat them.

His research spans a broad spectrum because abnormal rhythms can begin in a single cell and trigger the collapse of the entire circulatory system.

"The electrical activity of the heart is really the signal that tells the heart to contract," said Rudy, who also has appointments in the Department of Physiology and Biophysics and in the Department of Medicine's Division of Cardiology. "It allows the heart to pump blood in a synchronous manner."

Normally, the heart's natural pacemaker (called the sinus node) produces electrical impulses known as action potentials that spread throughout the heart like a wave, telling it to contract, Rudy explained.

"Governed by the sinus node, the wave of electrical excitation travels in a precisely defined path that is repeated during every heart beat."

Ordinarily this pattern occurs systematically. If a person has heart disease, fibrillation can occur, causing fast and irregular heartbeats. The heart's electrical impulses can become chaotic leading to sudden death.

He studies this phenomena through computer models and experimental observations. To do this, he must start with the individual cells that make up the heart muscle. These cells are connected by gap junctions, the structures that allow electrical communication between cells.

The CWRU researchers have developed a detailed mathematical model that allows them to predict electrical behavior of cardiac cells affected by heart disease and how to modify their activity with drugs and other treatments.

They are also investigating coupling problems which prevent the spread of electrical signals between cells. This can be caused by oxygen deprivation due to reduced blood flow from partial or complete blockage of coronary arteries.

Rudy also has received funding for continuing his research on a new diagnostic tool for electrocardiographic imaging (ECGI).

It is more advanced than the traditional electrocardiogram, which only measures electrical signals from six or 12 positions on the body surface, omitting important information. This forces the cardiologist to infer information about the electrical activity in the heart to diagnose and treat patients, a system that is prone to error.

"If you see a car coming toward you at night, and all you see is one headlight until the car is close to you, your ability to interpret what you are seeing is restricted," Rudy said.

A cardiologist should ideally have information directly from the heart, but this would require open-heart surgery placing an electrode "sock" over the heart surface, Rudy said.

With advances in computers and electronics, it is now possible to cover the torso with hundreds of electrodes mounted in a vest to obtain more specific information through a method called body surface potential mapping pioneered by CWRU researchers.

Rudy has developed mathematical methods to compute the electrical activity of the heart from such measurements. It allows the researchers to reconstruct the electric field on the surface of the heart from a complete map of body-surface ECG data in a completely noninvasive fashion.

"The result is a close approximation of the electrical measurements that would have been obtained by electrodes in direct contact with the heart, but without the need to approach the heart physically," Rudy said.

He hopes that the research will help diagnose rhythm disorders and identify patients at risk for sudden death. It also could assist surgeons in planning anti-arrhythmic heart surgery, steer them to affected sites, or help in guiding catheters to remove the foci of the arrhythmia without surgery. He believes that it may also be a noninvasive tool for evaluating the efficacy of anti-arrhythmic drug therapy and, in the future, of genetic and molecular interventions.

-CWRU-

Note: A color photo of Yoram Rudy is available on the Web at http://www.cwru.edu/pubaff/univcomm/rudy.gif.